Poor Breast Cancer Prognosis Associated With Low Vitamin D Levels

Research Summary: "Blood levels of vitamin D and early stage breast cancer prognosis: a systematic review and meta-analysis" by A.A. Rose et al.

Increasingly, researchers are exploring the link between vitamin D and disease, particularly breast cancer. As with most research along these lines, the topic is controversial. While some studies have associated a higher incidence of breast cancer among women with low serum levels of vitamin D, others have not. Because vitamin D regulates the immune system, as well as the expression of genes related to the development and prognosis of breast cancer, a thorough understanding of the role vitamin D plays in the progression of the illness is critical.

In order to examine the evidence linking vitamin D levels to breast cancer, a group of researchers from McGill and the University of Toronto in Canada conducted a systematic meta-analysis of research articles published between 1982 and 2013. The team searched three sources: Medline (1982-May 2013), the American Society of Clinical Oncology (2009-2012), and the San Antonio Breast Cancer Symposium (2010-2012) for articles related to early stage breast cancer and vitamin D. In all, they found eight qualifying studies, encompassing a total of 5,691 patients.

Among these patients, 36.8 % of the women were classified as deficient in vitamin D. When compared to women with high vitamin D levels, those with the lowest serum D levels had double the risk of recurrence (six studies). The risk of death was increased by 76% (four studies).

The authors concluded that these findings “support an association of low levels of vitamin D with increased risk of recurrence and death in early stage breast cancer patients.”